Lightfast colorant and lightfast ink composition including the same

ABSTRACT

A lightfast colorant and a lightfast ink composition include a lightfast colorant that is derived by covalently binding a benzophenone derivative and a conventional colorant and that imparts effective lightfastness and long-term storage stability to an ink composition that is prepared with the same.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the priority of Korean Patent ApplicationNo. 2003-17746, filed on Mar. 21, 2003, in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein in itsentirety by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a lightfast colorant and alightfast ink composition including the same, and more particularly, toa lightfast colorant that is derived by chemically binding abenzophenone derivative to the molecular structure of a conventionalcolorant, and a lightfast ink composition containing the same.

[0004] 2. Description of the Related Art

[0005] Ink-jet printing, which is a kind of non-impact printing, has theadvantages of low noise generation, compared to impact printing, andeasy color printing realization, compared to laser beam printing.

[0006] There are two types of non-impact printing: continuous ink-jetprinting and drop-on-demand (DOD) printing. In continuous ink-jetprinting, while ink is continuously discharged, a change in anelectromagnetic field is induced to control a direction in which the inkis jetted. DOD printing, in which micro droplets of ink are jetted,includes thermal-bubble ink-jet printing and piezoelectric ink-jetprinting. In thermal-bubble ink-jet printing, ink is discharged by apressure generated by the swelling of bubbles that are generated as theink is heated. In piezoelectric ink-jet printing, ink is discharged by apressure generated by using a piezoelectric plate that may bemechanically deformable by electricity.

[0007] Recently, a dot-size of ink-jet printers utilized has becomesmaller, and there has been an increasing need for high-resolution,high-quality prints. Smaller dot-size ink-jet printers require a headhaving smaller nozzle orifices. However, smaller nozzle orifices aresusceptible to being clogged by precipitates, and thus affect the sizeof ink droplets and the performance of the printer. It is obvious thatthe composition of the ink affects the clogging of the nozzle orifices.For this reason, a wetting agent is commonly added to the ink-jet inkcompositions.

[0008] An ink composition for ink-jet printing contains a colorant, asolvent, and an additive. A dye or a pigment may be used as thecolorant. However, using a dye as the colorant is limited because itcauses a print to have poor lightfast and water-fast properties. Whenusing a pigment as the colorant, a resulting print is more lightfast andwater-fast than a print prepared using a dye, but is still susceptibleto color change or discoloration when exposed to ultraviolet (UV) light.An additional lightfastness enhancer may be used. However, negative sideeffects, for example, the clogging of the nozzle orifices byagglomerated ink, the formation of a heterogeneous ink composition, andthe like, occur when the lightfastness enhancer is used.

[0009] As an example, EP 1006161 A1 discloses an ink composition inwhich a colorant covered with a polymer that includes UV-absorbingand/or lightfast sites is dispersed. The ink composition that includessuch a colorant coated with a UV-absorbing polymer is unstable due topoor dispersion stability of the polymer-coated colorant particles andthe weak binding force between the colorant and the polymer.

SUMMARY OF THE INVENTION

[0010] The present invention provides a lightfast colorant thatminimizes the above-listed and/or other problems.

[0011] The present invention provides a lightfast ink composition thatcontains the lightfast colorant.

[0012] In one aspect of the present invention, a lightfast colorantcomprises a benzophenone derivative of formula (1) below:

[0013] wherein Y₁ is one selected from the group consisting of —H, —OH,—NH₂, —NHR₁, —N(R₁)₂, —SH, and a C₁-C₃₀ heteroalkyl group, where R₁ is aC₁-C₆ alkyl group; each of Y₂ and Y₃, which may be the same ordifferent, is independently selected from the group consisting of —H,—OH, —NH₂, —NHR₁, —N(R₁)₂, where R₁ is a C₁-C₆ alkyl group, —SH, asubstituted or unsubstituted C₁-C₃₀ alkyl group, a substituted orunsubstituted C₁-C₃₀ alkenyl group, a substituted or unsubstitutedC₁-C₃₀ alkynyl group, a substituted or unsubstituted C₁-C₃₀ heteroalkylgroup, a substituted or unsubstituted C₆-C₃₀ aryl group, a substitutedor unsubstituted C₇-C₃₀ arylalkyl group, a substituted or unsubstitutedC₃-C₃₀ heteroaryl group, and a substituted or unsubstituted C₄-C₃₀heteroarylalkyl group; n is an integer from 0 to 6; R is selected fromthe group consisting of a substituted or unsubstituted C₁-C₃₀ alkylenegroup, a substituted or unsubstituted C₁-C₃₀ alkenylene group, asubstituted or unsubstituted C₁-C₃₀alkynylene group, a substituted orunsubstituted C₁-C₃₀ heteroalkylene group, a substituted orunsubstituted C₆-C₃₀ arylene group, a substituted or unsubstitutedC₇-C₃₀ arylenealkylene group, a substituted or unsubstituted C₃-C₃₀heteroarylene group, and a substituted or unsubstituted C₄-C₃₀heteroarylenealkylene group;

[0014] X is a linker selected from the group consisting of —CONH—,—NHCO—, —COO—, —OCO—, —CO—, —O—, —S—, —SO₂—, —SO₃—, —O—P(═O)(OH)—O—, and—O—P(OH)—O—; and Y is a colorant residue.

[0015] The colorant residue Y is a remaining moiety of a colorant, whichmay be either a dye or a pigment, the moiety excluding the linker X thatis an amide bond, an ester bond, a carbonyl bond, a sulfonyl bond, andthe like, and links the colorant and a benzophenone derivative. Thelinker X is formed by a condensation reaction between a functional groupin the molecular structure of the colorant (dye or pigment), such as ahydroxy group, an amino group, a sulfonic acid group, a phosphoric acidgroup, and the like, and a functional group of the benzophenonederivative, such as a hydroxy group, an amine group, a carboxyl group,and the like.

[0016] In another aspect of the present invention, a lightfast inkcomposition includes at least one of the lightfast colorants havingformula (1) above and an aqueous medium.

[0017] Another lightfast ink composition, according to an embodiment ofthe present invention, includes a colorant, at least one of thelightfast colorants having formula (1) above, and an aqueous medium.

[0018] Additional aspects and/or advantages of the invention will be setforth in part in the description which follows and, in part, will beobvious from the description, or may be learned by practice of theinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Embodiments of a lightfast colorant according to an embodiment ofthe present invention will be described in detail.

[0020] A lightfast colorant according to an embodiment of the presentinvention is derived by chemically binding a lightfast enhancer and acolorant. In other words, a lightfast colorant according to anembodiment of the present invention is obtained by chemically binding aconventional colorant and a benzophenone derivative. The lightfastcolorant according to an embodiment of the present invention improvesthe long-term storage stability of an ink composition without requiringadding a separate lightfastness enhancer. Also, since water solublefunctional groups, such as an amino group, a hydroxy group, a carboxylgroup, a sulfonic acid group, a phosphoric acid group, and the like, areconverted into an amide group, an ester group, a carbonyl group, or asulfonyl group, the water-fastness of a resulting print is alsoimproved.

[0021] A lightfast colorant according to an embodiment of the presentinvention is a benzophenone derivative of formula (1) below:

[0022] In formula (1) above, Y₁ is one selected from the groupconsisting of —H, —OH, —NH₂, —NHR₁, —N(R₁)₂, —SH, and a C₁-C₃₀heteroalkyl group, where R₁ is a C₁-C₆ alkyl group; each of Y₂ and Y₃,which may be the same, is independently selected from the groupconsisting of —H, —OH, —NH₂, —NHR₁, —N(R₁)₂, where R₁ is a C₁-C₆ alkylgroup, —SH, a substituted or unsubstituted C₁-C₃₀alkyl group, asubstituted or unsubstituted C₁-C₃₀ alkenyl group, a substituted orunsubstituted C₁-C₃₀ alkynyl group, a substituted or unsubstitutedC₁-C₃₀ heteroalkyl group, a substituted or unsubstituted C₆-C₃₀ arylgroup, a substituted or unsubstituted C₇-C₃₀ arylalkyl group, asubstituted or unsubstituted C₃-C₃₀ heteroaryl group, and a substitutedor unsubstituted C₄-C₃₀ heteroarylalkyl group; n is an integer from 0 to6; R is selected from the group consisting of a substituted orunsubstituted C₁-C₃₀ alkylene group, a substituted or unsubstitutedC₁-C₃₀ alkenylene group, a substituted or unsubstituted C₁-C₃₀alkynylene group, a substituted or unsubstituted C₁-C₃₀ heteroalkylenegroup, a substituted or unsubstituted C₆-C₃₀ arylene group, asubstituted or unsubstituted C₇-C₃₀ arylenealkylene group, a substitutedor unsubstituted C₃-C₃₀ heteroarylene group, and a substituted orunsubstituted C₄-C₃₀ heteroarylenealkylene group; X is a linker selectedfrom the group consisting of —CONH—, —NHCO—, —COO—, —OCO—, —CO—, —O—,—S—, —SO₂—, —SO₃—, —O—P(═O)(OH)—O—, and —O—P(OH)—O—; and Y is a colorantresidue.

[0023] The colorant residue Y refers to a remaining moiety of thecolorant, which may be either a dye or a pigment, the moiety excludingthe linker X that is an amide bond, an ester bond, a carbonyl bond, asulfonyl bond, and the like, and links the colorant and a benzophenonederivative.

[0024] The linker X is formed by a condensation reaction between afunctional group in the molecular structure of the colorant (dye orpigment), such as a hydroxy group, an amino group, a sulfonic acidgroup, a phosphoric acid group, and the like, and a functional group ofthe benzophenone derivative, such as a hydroxy group, an amine group, acarboxyl group, and the like.

[0025] The lightfast colorant according to an embodiment of the presentinvention is derived by chemically binding a colorant having afunctional group as described above and a benzophenone derivative thatimparts lightfastness. In other words, the lightfast colorant of formula(1) according to an embodiment of the present invention may be obtainedby covalently binding a colorant and a benzophenone derivative offormula (2) below through a chemical bond, such as an amide bond, anester bond, a carbonyl bond, a sulfonyl bond, and the like.

[0026] In formula (2) above, Y₁, Y₂, Y₃, n, and R are the same as informula (1) above; and X′ is a reactive functional group selected fromthe group consisting of a carboxyl group, a hydroxy group, an aminogroup, a sulfonic acid group, and a phosphoric acid group.

[0027] As illustrated in the following reaction schemes (1) through (4),the lightfast colorant of formula (1) according to an embodiment of thepresent invention is derived by a condensation reaction of a carboxylgroup, a hydroxy group, an amino group, a sulfonic acid group, aphosphoric acid group, and the like, which are present in the molecularstructure of a source colorant and the reactive functional group X′ ofthe benzophenone derivative of formula (2).

[0028] In Reaction schemes (1) through (4) above, Y₁, Y₂, Y₃, n, and Rare the same as in formula (1).

[0029] The colorant that is chemically bound with the benzophenonederivative of formula (2) is expressed as HO—Y, H₂N—Y, and HOOC—Y, whereY refers to the above-described colorant residue, in the reactionschemes (1) through (4) and may be any dye or pigment that is commonlyused in ink compositions provided that it includes an amino group, acarboxyl group, a hydroxyl group, a phosphoric acid group, a sulfonicacid group, and the like, which may react with the reactive functionalgroup X′ of the benzophenone derivative of formula (2) in the molecularstructure thereof. Specific examples of a dye include, but are notlimited to, C.I DIRECT BLACK NOS. 9, 17, 19, 22, 32, 51, 56, 91, 94, 97,166, 168, 173, and 199; C.I DIRECT BLUE NOS. 1, 10, 15, 22, 77, 78, 80,200, 201, 202, 203, 207, and 211; C.I DIRECT RED NOS. 2, 4, 9, 23, 31,39, 63, 72, 83, 84, 89, 111, 173, 177, 184, and 240; C.I DIRECT YELLOWNOS. 8, 9, 11, 12, 27, 28, 29, 33, 35, 39, 41, 44, 50, 53, and 58; andother direct dyes, disperse dyes, basic dyes, acid dyes, azo dyes, andthe like. Specific examples of a pigment for the colorant include, butare not limited to, carbon black, graphite, vitreous carbon, activatedcharcoal, activated carbon, anthraquinones, phthalocyanine blue,phthalocyanine green, diazos, monoazos, pyranthrones, perylenes,quinacridones, and indigoid pigments.

[0030] As described above, in formulas (1) and (2), Y₁ is one selectedfrom the group consisting of —H, —OH, —NH₂, —NHR₁, —N(R₁)₂, —SH, and aC₁-C₃₀ heteroalkyl group, where R₁ is a straight or branched C₁-C₆ alkylgroup.

[0031] The heteroallyl group for Y₁ is a straight or branchedheteroalkyl group having 1 to 30 carbon atoms, preferably, 1 to 20carbon atoms, more preferably, 1 to 10 carbon atoms. The C₁₀-C₃₀heteroalkyl group for Y₁ is a C₁-C₃₀ alkyl group including 1 to 3 heteroatoms selected from the group consisting of N, O, P, and S. Specificexamples of such a heteroalkyl group include, but are not limited to, anoxymethyl group, an oxyethyl group, an oxypropyl group, a mercaptomethylgroup, a mercaptoethyl group, a mercaptopropyl group, and the like. Atleast one hydrogen atom in the heteroalkyl group may be substituted witha halogen atom, a haloalkyl group, an alkoxyl group, a hydroxyl group, anitro group, a cyano group, an amino group, a lower alkyl amino group,an amidino group, hydrazine, hydrazone, a carboxyl group or a saltthereof, a sulfonic acid group or a salt thereof, a phosphoric acidgroup or a salt thereof, and the like.

[0032] As described above, Y₂ and Y₃ in formulas (1) and (2), which maybe the same or different, are independently selected from the groupconsisting of —H, —OH, —NH₂, —NHR₁, —N(R₁)₂, where R₁ is a straight orbranched C₁-C₆alkyl group, —SH, a substituted or unsubstituted C₁-C₃₀alkyl group, a substituted or unsubstituted C₁-C₃₀alkenyl group, asubstituted or unsubstituted C₁-C₃₀ alkynyl group, a substituted orunsubstituted C₁-C₃₀ heteroalkyl group, a substituted or unsubstitutedC₆-C₃₀ aryl group, a substituted or unsubstituted C₇-C₃₀ arylalkylgroup, a substituted or unsubstituted C₃-C₃₀ heteroaryl group, and asubstituted or unsubstituted C₄-C₃₀ heteroarylalkyl group.

[0033] The alkyl group for Y₂ or Y₃ may be a straight or branched alkylgroup having 1 to 30 carbon atoms, preferably, 1 to 20 carbon atoms,more preferably, 1 to 10 carbon atoms. Specific examples of such analkyl group include, but are not limited to, a methyl group, an ethylgroup, an n-propyl group, an isopropyl group, an n-butyl group, anisobutyl group, a sec-butyl group, a t-butyl group, a pentyl group, aniso-amyl group, a hexyl group, a heptyl group, an octyl group, a nonylgroup, a decyl group, a dodecyl group, and the like, wherein at leastone hydrogen atom in the alkyl group may be substituted with a halogenatom, a haloalkyl group, an alkoxyl group, a hydroxyl group, a nitrogroup, a cyano group, an amino group, a lower alkyl amino group, anamidino group, hydrazine, hydrazone, a carboxyl group or a salt thereof,a sulfonic acid group or a salt thereof, a phosphoric acid group or asalt thereof, and the like.

[0034] The alkenyl group for Y₂ or Y₃ may be a straight or branchedalkenyl group having 1 to 30 carbon atoms, preferably, 1 to 20 carbonatoms, more preferably, 1 to 10 carbon atoms. The alkenyl group refersto an alkyl group that includes at least one carbon-carbon double bondin its molecular structure. Specific examples of such an alkenyl groupinclude, but are not limited to, an ethylene group, a propylene group, abutylene group, a hexylene group, an allyl group, and the like. At leastone hydrogen atom of the alkenyl group may be substituted with a halogenatom, a haloalkyl group, an alkoxyl group, a hydroxyl group, a nitrogroup, a cyano group, an amino group, a lower alkyl amino group, anamidino group, hydrazine, hydrazone, a carboxyl group or a salt thereof,a sulfonic acid group or a salt thereof, a phosphoric acid group or asalt thereof, and the like.

[0035] The alkynyl group for Y₂ or Y₃ may be a straight or branchedalkynyl group having 1 to 30 carbon atoms, preferably, 1 to 20 carbonatoms, more preferably, 1 to 10 carbon atoms. The alkynyl group refersto an alkyl group that includes at least one carbon-carbon triple bondin its molecular structure. Specific examples of such an alkynyl groupinclude, but are not limited to, an acetylenyl group, a propylenylgroup, and the like. At least one hydrogen atom of the alkynyl group maybe substituted with a halogen atom, a haloalkyl group, an alkoxyl group,a hydroxyl group, a nitro group, a cyano group, an amino group, a loweralkyl amino group, an amidino group, hydrazine, hydrazone, a carboxylgroup or a salt thereof, a sulfonic acid group or a salt thereof, aphosphoric acid group or a salt thereof, and the like.

[0036] The heteroalkyl group for Y₂ or Y₃ may be a straight or branchedheteroalkyl group having 1 to 30 carbon atoms, preferably, 1 to 20carbon atoms, more preferably, 1 to 10 carbon atoms. The C₁₀-C₃₀heteroalkyl group for each of Y₂ and Y₃ is a C₁-C₃₀ alkyl groupincluding 1 to 3 hetero atoms selected from the group consisting of N,O, P, and S. Specific examples of such a heteroalkyl group include, butare not limited to, an oxymethyl group, an oxyethyl group, an oxypropylgroup, a mercaptomethyl group, a mercaptoethyl group, a mercaptopropylgroup, and the like. At least one hydrogen atom in the heteroalkyl groupmay be substituted with a halogen atom, a haloalkyl group, an alkoxylgroup, a hydroxyl group, a nitro group, a cyano group, an amino group, alower alkyl amino group, an amidino group, hydrazine, hydrazone, acarboxyl group or a salt thereof, a sulfonic acid group or a saltthereof, a phosphoric acid group or a salt thereof, and the like.

[0037] The aryl group for Y₂ or Y₃ may be an aryl group having 6 to 30carbon atoms, preferably, 6-18 carbon atoms, and more preferably, 6 to12 carbon atoms, the aryl group being a hydrocarbon group that includesat least one aromatic ring. Specific examples of such an aryl groupinclude, but are not limited to, aromatic radicals, such as phenyl,naphthyl, biphenyl, tetrahydronaphthyl, indanyl, and the like, withphenyl and naphthyl being preferred. At least one hydrogen atom in thearyl group may be substituted with a halogen atom, a haloalkyl group, analkoxyl group, a hydroxyl group, a nitro group, a cyano group, an aminogroup, a lower alkyl amino group, an amidino group, hydrazine,hydrazone, a carboxyl group or a salt thereof, a sulfonic acid group ora salt thereof, a phosphoric acid group or a salt thereof, and the like.

[0038] The substituted or unsubstituted arylalkyl group for each of Y₂and Y₃ may have 7 to 30 carbon atoms, preferably, 7 to 19 carbon atoms,more preferably, 7 to 13 carbon atoms. Specific examples of such anarylalkyl group include, but are not limited to, benzyl, phenetyl,triphenylmethyl, diphenylmethyl, phenylbutyl, neophyl, and the like. Atleast one hydrogen atom in the arylalkyl group may be substituted with ahalogen atom, a haloalkyl group, an alkoxyl group, a hydroxyl group, anitro group, a cyano group, an amino group, a lower alkyl amino group,an amidino group, hydrazine, hydrazone, a carboxyl group or a saltthereof, a sulfonic acid group or a salt thereof, a phosphoric acidgroup or a salt thereof, and the like. The arylalkyl group for each ofY₂ and Y₃ may include a carbon-carbon double bond or carbon-carbontriple bond in its alkyl residue, like a styryl group.

[0039] The substituted or unsubstituted heteroaryl group for each of Y₂and Y₃ may have 3 to 30 carbon atoms, preferably, 3 to 18 carbon atoms,more preferably, 3 to 12 carbon atoms. The heteroaryl group refers to anaromatic carbocyclic system that contains one, two, or three heteroatoms selected from the group consisting of N, O, P, and S, wherein atleast one of the hetero atoms may be oxidized or quaternarized into, anN-oxide or a quaternary salt. Examples of such a heteroaryl groupinclude, but are not limited to, thienyl, benzothienyl, pyridyl,pyrazinyl, pyrimidinyl, pyridazinyl, quinolinyl, quinoxalinyl,imidazolyl, furanyl, benzofuranyl, thiazolyl, isoxazolyl,benzisoxazolyl, benzimidazolyl, triazolyl, pyrazolyl, pyrrolyl, indolyl,2-pyridonyl, 4-pyridonyl, N-alkyl-2-pyridonyl, pyrazinonyl,pyridazinonyl, pyrimidinonyl, oxazolonyl, an N-oxide of the foregoinggroups, such as pyridyl N-oxide and quinolinyl N-oxide, and a quaternarysalt of the foregoing materials, and the like. At least one hydrogenatom in the heteroaryl group may be substituted with a halogen atom, ahaloalkyl group, an alkoxyl group, a hydroxyl group, a nitro group, acyano group, an amino group, a lower alkyl amino group, an amidinogroup, hydrazine, hydrazone, a carboxyl group or a salt thereof, asulfonic acid group or a salt thereof, a phosphoric acid group or a saltthereof, and the like.

[0040] The substituted or unsubstituted heteroarylalkyl group for eachof Y₂ and Y₃ may have 4 to 30 carbon atoms, preferably, 4 to 18 carbonatoms, more preferably, 4 to 12 carbon atoms. The heteroarylalkyl grouprefers to a heteroaryl group that has an alkyl group substituted forsome hydrogen atom. Examples of such a heteroarylalkyl group include,but are not limited to, thienylmethyl, thienylethyl, benzothienylmethyl,benzothienylethyl, pyridylmethyl, pyridylethyl, pyridylpropyl,pyrazinylmethyl, pyrazinylethyl, pyrimidinylmethyl, pyrimidinylethyl,pyridazinylmethyl, pyridazinylethyl, quinolinylmethyl, quinolinylethyl,quinoxalinylmethyl, quinoxalinylethyl, imidazolylmethyl,imidazolylethyl, furanylmethyl, furanylethyl, and the like. At least onehydrogen atom in the heteroarylalkyl group may be substituted with ahalogen atom, a haloalkyl group, an alkoxyl group, a hydroxyl group, anitro group, a cyano group, an amino group, a lower alkyl amino group,an amidino group, hydrazine, hydrazone, a carboxyl group or a saltthereof, a sulfonic acid group or a salt thereof, a phosphoric acidgroup or a salt thereof, and the like.

[0041] In formula (1) and (2) above, R is selected from the groupconsisting of a substituted or unsubstituted C₁-C₃₀ alkylene group, asubstituted or unsubstituted C₁-C₃₀alkenylene group, a substituted orunsubstituted C₁-C₃₀ alkynylene group, a substituted or unsubstitutedC₁-C₃₀ heteroalkylene group, a substituted or unsubstituted C₆-C₃₀arylene group, a substituted or unsubstituted C₇-C₃₀ arylenealkylenegroup, a substituted or unsubstituted heteroarylene group, and asubstituted or unsubstituted C₄-C₃₀ heteroarylenealkylene group. Thealkylene group, alkenylene group, alkynylene group, heteroalkylenegroup, arylene group, arylenealkylene (or alkylenearylene) group,heteroarylene group, and heteroarylenealkylene (orheteroalkylenearylene) group are divalent radicals that may beincorporated in the middle of compounds and which correspond to an alkylgroup, alkenyl group, alkynyl group, heteroalkyl group, aryl group,arylalkyl group, heteroaryl group, and heteroarylalkyl group,respectively, which are monovalent radicals positioned at an end ofcompounds.

[0042] The alkylene group for R may be a straight or branched radicalhaving 1 to 30 carbon atoms, preferably, 1 to 20 carbon atoms, morepreferably, 1 to 10 carbon atoms. Specific examples of such an alkylenegroup include, but are not limited to, a methylene group, an ethylenegroup, a n-propylene group, an isopropylene group, a n-butylene group,an isobutylene group, a sec-butylene group, a t-butylene group, an-pentylene group, a sec-pentylene group, a t-pentylene group, ahexylene group, a heptylene group, an octylene group, a nonylene group,a decylene group, a dodecylene group, and the like. At least onehydrogen atom in the alkylene group may be substituted with a halogenatom, a haloalkyl group, an alkoxyl group, a hydroxyl group, a nitrogroup, a cyano group, an amino group, a lower alkyl amino group, anamidino group, hydrazine, hydrazone, a carboxyl group or a salt thereof,a sulfonic acid group or a salt thereof, a phosphoric acid group or asalt thereof, and the like.

[0043] The alkenylene group or alkynylene group for R may have 1 to 30carbon atoms, preferably, 1 to 20 carbon atoms, more preferably, 1 to 10carbon atoms. The C₁-C₃₀ alkenylene group and C₁-C₃₀ alkynylene groupcorrespond to the C₁-C₃₀alkylene groups, the only difference being thatthey have at least one carbon-carbon double bond or carbon-carbon triplebond, respectively. At least one hydrogen atom in the alkenylene oralkynylene group may be substituted with a halogen atom, a haloalkylgroup, an alkoxyl group, a hydroxyl group, a nitro group, a cyano group,an amino group, a lower alkyl amino group, an amidino group, hydrazine,hydrazone, a carboxyl group or a salt thereof, a sulfonic acid group ora salt thereof, a phosphoric acid group or a salt thereof, and the like.

[0044] The heteroalkylene group for R may have 1 to 30 carbon atoms,preferably, 1 to 20 carbon atoms, more preferably, 1 to 10 carbon atoms.The heteroalkylene group refers to an alkylene group that includes one,two, or three hetero atoms selected from the group consisting of N, O,P, and S. Specific examples of such a heteroalkylene group include anoxymethylene group, an oxyethylene group, a propoxy group, amercaptomethylene group, a mercaptoethylene group, a mercaptopropoxygroup, and the like. At least one hydrogen atom in the heteroalkylenegroup may be substituted with a halogen atom, a haloalkyl group, analkoxyl group, a hydroxyl group, a nitro group, a cyano group, an aminogroup, a lower alkyl amino group, an amidino group, hydrazine,hydrazone, a carboxyl group or a salt thereof, a sulfonic acid group ora salt thereof, a phosphoric acid group or a salt thereof, and the like.

[0045] The arylene group for R may have 6 to 30 carbon atoms,preferably, 6 to 18 carbon atoms, more preferably, 1 to 12 carbon atoms.Specific examples of such an arylene group include, but are not limitedto, aromatic groups, such as a phenylene group, a naphthylene group, abiphenylene group, a tetrahydronaphthylene group, an indanylene group,and the like, with the biphenylene group, biphenylene group, andnathphylene group being preferred. At least one hydrogen atom in thearylene group may be substituted with a halogen atom, a haloalkyl group,an alkoxyl group, a hydroxyl group, a nitro group, a cyano group, anamino group, a lower alkylamino group, an amidino group, hydrazine,hydrazone, a carboxyl group or a salt thereof, a sulfonic acid group ora salt thereof, a phosphoric acid group or a salt thereof, and the like.

[0046] The arylenealkylene group for R may have 7 to 30 carbon atoms,preferably, 7 to 19 carbon atoms, more preferably, 7 to 13 carbon atoms.The arylenealkylene group refers to a divalent radical corresponding toan arylalkyl group and comprises an alkylenearylene group. Specificexamples of such an arylenealkylene group include, but are not limitedto, a methylenephenylene group, an ethylenephenylene group, amethylenenaphthylene group, an ethylenenaphthylene group, amethylenebiphenylene group, an ethylenebiphenylene group, ann-propylenephenylene group, an iso-propylenephenylene group, and thelike. At least one hydrogen atom in the arylenealkylene group may besubstituted with a halogen atom, a haloalkyl group, an alkoxyl group, ahydroxyl group, a nitro group, a cyano group, an amino group, a loweralkylamino group, an amidino group, hydrazine, hydrazone, a carboxylgroup or a salt thereof, a sulfonic acid group or a salt thereof, aphosphoric acid group or a salt thereof, and the like.

[0047] The heteroarylene group for R may have 3 to 30 carbon atoms,preferably, 3 to 18 carbon atoms, more preferably, 3 to 12 carbon atoms.The heteroarylene group refers to a divalent aromatic, carbocyclicsystem containing one, two, or three hetero atoms as an aromatic ringbackbone atom selected from the group consisting of N, O, P, and S. Theheteroarylene group includes a divalent arylene group that has a heteroatom oxidized or quaternarized into, for example, an N-oxide or aquaternary salt. Specific examples of such a heteroarylene groupinclude, but are not limited to, thienylene, benzothienylene,pyridylene, pyrazinylene, pyrimidinylene, pyridazinylene, quinolinylene,quinoxalinylene, imidazolylene, furanylene, benzofuranylene,thiazolylene, isoxazolylene, benzisoxazolylene, benzimidazolylene,triazolylene, pyrazolylene, pyrrolylene, indolylene, 2-pyridonylene,4-pyridonylene, N-alkyl-2-pyrinonylene, pyrazinonylene,pyridazinonylene, pyrimidinonylene, oxazolonylene, an N-oxide of theforegoing groups, such as pyridylene N-oxide and quinolinylene N-oxide,and a quaternary salt of the foregoing groups. At least one hydrogenatom in the heteroarylene group may be substituted with a halogen atom,a haloalkyl group, an alkoxyl group, a hydroxyl group, a nitro group, acyano group, an amino group, a lower alkylamino group, an amidino group,hydrazine, hydrazone, a carboxyl group or a salt thereof, a sulfonicacid group or a salt thereof, a phosphoric acid group or a salt thereof,and the like.

[0048] The heteroarylenealkylene group for R may have 4 to 30 carbonatoms, preferably, 4 to 18 carbon atoms, more preferably, 4 to 12 carbonatoms. The heteroarylenealkylene group refers to a heteroarylene groupthat has alkylene groups substituted for some hydrogen atoms. Specificexamples of such a heteroarylenealkylene group include, but are notlimited to, thienylene methylene, thienylene ethylene, benzothienylenemethylene, benzothienylene ethylene, pyridylene methylene, pyridyleneethylene, pyrazinylene methylene, pyrazinylene ethylene, pyrimidinylenemethylene, pyrimidinylene ethylene, pyridazinylene methylene,pyridazinylene ethylene, quinolinylene methylene, quinolinyleneethylene, quinoxalinylene methylene, quinoxalinylene ethylene,imidazolylene methylene, imidazolylene ethylene, furanylene methylene,furanylene ethylene, and the like. At least one hydrogen atom in theheteroarylenealkylene group may be substituted with a halogen atom, ahaloalkyl group, an alkoxyl group, a hydroxyl group, a nitro group, acyano group, an amino group, a lower alkylamino group, an amidino group,hydrazine, hydrazone, a carboxyl group or a salt thereof, a sulfonicacid group or a salt thereof, a phosphoric acid group or a salt thereof,and the like.

[0049] Specific examples of the lightfast colorant of formula (1) aboveinclude lightfast colorants having formulas (3) through (8) below.

[0050] In formulas (3) through (8) above, Y₁, Y₂, Y₃, R, n, and X arethe same as in formula (1) above.

[0051] Hereinafter, a lightfast ink composition that includes theabove-described lightfast colorant of formula (1) according to anembodiment of the present invention will be described in detail.

[0052] An ink composition according to an embodiment of the presentinvention includes only the above lightfast colorant as a colorantcomponent and does not include an additional conventional colorant. Anink composition according to an embodiment of the present inventionincludes at least one of the above-listed lightfast colorants, whichhave formula (1), and an aqueous medium. This ink composition mayinclude 0.1-20 parts by weight, preferably, 1-10 parts by weight, of thelightfast colorant with respect to 100 parts by weight of the inkcomposition.

[0053] An ink composition according to another embodiment of the presentinvention includes both a conventional colorant and the lightfastcolorant according to an embodiment of the present invention. Inparticular, the ink composition includes a conventional colorant, atleast one of the above-listed lightfast colorants according to anembodiment of the present invention, which have formula (1), and anaqueous medium. This ink composition may include 1-25 parts by weight ofthe conventional colorant and 0.1-20 parts by weight of at least one ofthe lightfast colorants according to an embodiment of the presentinvention. A total amount of the conventional colorant and the lightfastcolorant according to an embodiment of the present invention may be inthe range of 1.1-45 parts by weight, preferably, 2-20 parts by weight,with respect to 100 parts by weight of the ink composition.

[0054] The ink compositions in the above embodiments of the presentinvention, including the conventional colorant and the lightfastcolorant according to an embodiment of the present invention, aredissolved or dispersed in an aqueous medium.

[0055] The aqueous medium may be water alone, or a mixture of 5-50% byweight of an organic solvent and 50-95% by weight of water. The amountsof water and the organic solvent in the aqueous medium may be varieddepending on various factors, for example, desired characteristics, suchas the viscosity, surface tension, drying speed, and the like, of theink composition. Desirable characteristics of ink compositions depend onprinting methods of printers and types of printing media.

[0056] Examples of an organic solvent that may be used for the aqueousmedium include, but are not limited to, alcohols, such as methylalcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butylalcohol, sec-butyl alcohol, t-butyl alcohol, isobutyl alcohol, and thelike; ketones, such as acetone, methylethyl ketone, diethyl ketone,diacetone alcohol, and the like; esters, such as methyl acetate, ethylacetate, ethyl lactate, and the like; polyhydric alcohols, such asethylene glycol, diethylene glycol, triethylene glycol, propyleneglycol, butylene glycol, 1,4-butane diol, 1,2,4-butane triol,1,5-pentanediol, 1,2,6-hexane triol, hexylene glycol, glycerol, glycerolethoxylate, trimethylolpropane ethoxylate, and the like; ethers, such asethylene glycol monomethyl ether, ethylene glycol monoethyl ether,diethylene glycol methyl ether, diethylene glycol ethyl ether,triethylene glycol monomethyl ether, triethylene glycol monoethyl ether,and the like; nitrogen-containing compounds, such as 2-pyrrolidone,N-methyl-2-pyrrolidone, and the like; and sulfur-containing compounds,such as dimethyl sulfoxide, tetramethylene sulfone, and thioglycol.

[0057] Each of the ink compositions according to the above embodimentsof the present invention may further include at least one additiveselected from the group consisting of a dispersant, a viscosityadjuster, a surfactant, a storage stabilizer, and a wetting agent.

[0058] When a pigment or a water-insoluble dye is used as the colorant,at least one dispersant may be added to the ink composition to improvethe dispersion stability of the colorant. Any dispersants, includingsimpler structure, lower molecular weight dispersants, and largermolecular weight dispersants, such as block copolymers, which are notdetrimental to physical properties, such as stability, and functionalityof the ink composition, may be used without limitation.

[0059] Specific examples of lower molecular weight, simpler structuredispersants include, but are not limited to, polyvinyl alcohol (PVA),cellulosics, ethylene oxide modified phenols, an ethyleneoxide/propylene oxide polymer, a sodium polyacrylate solution (TEGO,DISPERSE 715W), a modified polyacryl resin solution (TEGO, DISPERSE735W), a solution of alkylol ammonium salt of a low molecular weightcarboxylic polymer (BYK-CHEMIE, DISPERBYK), a solution of alkylolammonium of a multifunctional polymer (BYK-CHEMIE, DISPERBYK-181), andmixtures of the foregoing dispersants.

[0060] Specific examples of complex, larger molecular weight dispersantsinclude, but are not limited to, siloxanes, such as a polyester siloxanecopolymer (TEGO, WET KL 245/WET 260), and hydrophilic polymers havingthe structure of AB or BAB type, wherein A is a hydrophobic homopolymeror copolymer of an unsubstituted or substituted C₁-C₃₀ acrylic monomerand B is a hydrophilic polymer or copolymer of a unsubstituted orsubstituted C₁-C₃₀ acrylic polymer. More specific examples of thecomplex, larger molecular weight dispersants include, but are notlimited to, an acrylic acid/acrylate copolymer, a methacrylicacid/methacrylate copolymer, an acrylicacid/polydialkylsiloxane/acrylate block copolymer, and a mixture of theforegoing polymers.

[0061] In each of the above-described ink compositions according toembodiments of the present invention, the amount of the dispersant maybe in the range of 0.1-20 parts by weight with respect to 100 parts byweight of the ink composition.

[0062] The viscosity adjuster in each of the ink compositions adjuststhe viscosity of the ink composition for smoother jetting. Specificexamples of such a viscosity adjuster include, but are not limited to,casein, hydroxymethylcellulose, hydroxyethylcellulose,carboxymethylcellulose, and the like. The amount of the viscosityadjuster may be in the range of 0.1-5.0 parts by weight with respect to100 parts by weight of the ink composition.

[0063] In each of the above ink compositions according to embodiments ofthe present invention, the amount of the dispersant may be in the rangeof 1-20 parts by weight with respect to 100 parts by weight of the inkcomposition.

[0064] The viscosity adjuster of each of the ink compositions adjuststhe viscosity of the ink composition for smoother jetting. Specificexamples of such a viscosity adjuster include, but are not limited to,casein, carboxymethylcellulose, and the like. The amount of theviscosity adjuster may be in the range of 0.1-5 parts by weight withrespect to 100 parts by weight of the ink composition.

[0065] In each of the above ink compositions according to an embodimentof the present invention, the amount of the surfactant may be in therange of 0.1-5 parts by weight with respect to 100 parts by weight ofthe ink composition. The surfactant of each of the ink compositionsaffects the surface tension of the composition such that the inkcomposition is more stably jetted through a nozzle. An anionicsurfactant or a nonionic surfactant may be used.

[0066] Examples of an anionic surfactant that may be used in the presentinvention include, but are not limited to, a salt of alkylcarboxylicacid having 1 to 1,000 carbon atoms, preferably, 10 to 200 carbon atoms,a salt of alcohol sulfonic acid ester having 1 to 1,000 carbon atoms,preferably, 10 to 200 carbon atoms, a salt of alkylsulfonic acid having1 to 1,000 carbon atoms, preferably, 10 to 200 carbon atoms, a salt ofalkylbenzene sulfonic acid having 1 to 1,000 carbon atoms, preferably,10 to 200 carbon atoms, and a mixture of the foregoing salts.

[0067] Examples of a nonionic surfactant that may be used in the presentinvention include, but are not limited to, polyoxyethylene alkyl etherhaving a C₁-C₁₀₀₀, preferably, C₁₀-C₂₀₀, alkyl group, polyoxyethylenealkyl phenyl ether having a C₁-C₁₀₀₀, preferably, C₁₀-C₂₀₀, alkyl group,polyoxyethylene secondary alkyl ether, a polyoxyethylene-oxypropyleneblock copolymer, polyglycerin fatty acid ester, a sorbitan fatty acidester, and a mixture of the foregoing materials.

[0068] In each of the above ink compositions according to embodiments ofthe present invention, the amount of the surfactant may be in the rangeof 0.1-5 parts by weight with respect to 100 parts by weight of the inkcomposition.

[0069] The wetting agent of each of the ink compositions preventsnozzles from clogging. A polyhydric alcohol may be used as the wettingagent. Specific examples of a wetting agent that may be used in thepresent invention include, but are not limited to, glycerin, ethyleneglycol, diethylene glycol, triethylene glycol, propylene glycol,dipropylene glycol, hexylene glycol, 1,3-butane diol, 1,4-butane diol,1.5-pentanediol, 2-butene-1,4-diol, and a mixture of the foregoingalcohols. In each of the above ink compositions according to embodimentsof the present invention, the amount of the wetting agent may be in therange of 10-30 parts by weight with respect to 100 parts by weight ofthe ink composition.

[0070] In each of the above ink compositions according to embodiments ofthe present invention, the total amount of at least one additiveselected from the group consisting of a dispersant, a viscosityadjuster, a surfactant, a storage stabilizer, and a wetting agent may bein the range of 0.5-40 parts by weight with respect to 100 parts byweight of the ink composition.

[0071] A method of preparing the above ink compositions, according to anembodiment of the present invention, will now be described.

[0072] The lightfast colorant and/or a general colorant and otheradditives, for example, a dispersant, a viscosity adjuster, asurfactant, and the like, are mixed together in an aqueous medium andthoroughly stirred to obtain a homogeneous composition. This compositionis passed through a filter having a pore size of 0.45-0.8 μm to obtainan ink composition according to an embodiment of the present invention.

[0073] Regarding the lightfast colorant according to an embodiment ofthe present invention, its sulfonic acid group (—SO₃H) may include ametallic sulfonate group, such as a sodium sulfonate group (—SO₃Na).

[0074] The present invention will be described in greater detail withreference to the following examples. The following examples are forillustrative purposes and are not intended to limit the scope of theinvention.

SYNTHESIS EXAMPLE 1

[0075] 2-hydroxy-4-(4-carboxy)phenyloxybenzophenone was synthesizedaccording to reaction scheme (5) below.

[0076] A 250-mL round-bottomed flask equipped with a reflux condenserwas charged with 150 mL of dimethylformamide (DMF) and 10.7 g of2,4-dihydxoxybenzophenone, and 1.2 g of sodium hydride was added whilesupplying nitrogen into the flask and stirred. 10 g of 4-bromobenzoicacid was slowly added into the mixture, heated slowly to about 60° C.while stirring it, and reacted for 5 hours. The reaction mixture wascooled to room temperature, and the reaction product was poured intoexcess distilled water to precipitate. The resulting precipitates werefiltered, washed several times with distilled water, and recrystallizedusing a solvent mixture of chloroform and ethanol to provide 9.5 g of2-hydroxy-4-(4-carboxy)phenyloxybenzophenone.

SYNTHESIS EXAMPLE 2

[0077] 2-hydroxy-4-(8-carboxy)octyloxybenzophenone was synthesizedaccording to reaction scheme (6) below.

[0078] 10 g of 2-hydroxy-4-(8-carboxy)octyloxybenzophenone wassynthesized in the same manner as in Synthesis Example 1, except that11.5 g of 8-bromooctanoic acid was used instead of 10 g of4-bromobenzoic acid.

SYNTHESIS EXAMPLE 3

[0079] 2-hydroxy-4-(4-hydroxy)phenyloxybenzophenone was synthesizedaccording to reaction scheme (7) below.

[0080] 9.7 g of 2-hydroxy-4-(4-hydroxy)phenyloxybenzophenone wassynthesized in the same manner as in Synthesis Example 1, except that8.7 g of 4-bromophenol was used instead of 10 g of 4-bromobenzoic acid.

SYNTHESIS EXAMPLE 4

[0081] 2-hydroxy-4-(6-hydroxy)hexyloxybenzophenone was synthesizedaccording to reaction scheme (8) below.

[0082] 10.6 g of 2-hydroxy-4-(6-hydroxy)hexyloxybenzophenone wassynthesized in the same manner as in Synthesis Example 1, except that9.1 g of 6-bromo-1-hexanol was used instead of 10 g of 4-bromobenzoicacid.

SYNTHESIS EXAMPLE 5

[0083] 2-hydroxy-4-(4-amino)phenyloxybenzophenone was synthesizedaccording to reaction scheme (9) below.

[0084] 10.3 g of 2-hydroxy-4-(4-amino)phenyloxybenzohenone wassynthesized in the same manner as in Synthesis Example 1, except that8.6 g of 4-bromoaniline was used instead of 10 g of 4-bromobenzoic acid.

SYNTHESIS EXAMPLE 6

[0085] A lightfast colorant of formula (9) below was synthesized byreacting the benzophenone derivative obtained in Synthesis Example 1with a direct dye C.I. DIRECT BLACK 168.

[0086] A 250-mL round-bottomed flask equipped with a reflux condenserwas charged with 150 mL of an ethyl acetate solvent, 8.3 g of thebenzophenone derivative obtained in Synthesis Example 1, and 16.6 g ofC.I. DIRECT BLACK 168, and the reactants were dissolved in the solvent.10 mL of conc. sulfuric acid was slowly added together with one or twoboiling chips into the mixture and refluxed for 12 hours or longer. Thereaction product was washed with distilled water and the organic phasewas collected. This organic phase was concentrated and recrystallized toprovide 16.5 g of the lightfast colorant of formula (9).

SYNTHESIS EXAMPLE 7

[0087] A lightfast colorant of formula (10) below was synthesized byreacting the benzophenone derivative obtained in Synthesis Example 1with an acid dye ACID YELLOW 23.

[0088] 8.3 g of the benzophenone derivative obtained in SynthesisExample 1 was dissolved in 200 mL of dimethylsulfoxide (DMSO) in a500-mL round-bottomed flask equipped with a reflux. 3.0 g of SOCl₂ wasadded to the mixture and reacted at room temperature for 1 hour orlonger. A solution of 12.3 g of C.I. ACID YELLOW 23 in 200 mL of DMSOwas added into the flask together with one or two boiling chips andreacted at 80° C. for 8 hours or longer. The reaction product was cooledto room temperature, and an excess of methanol was added to precipitatea desired crystalline compound. The crystalline precipitates werefiltered by suction and washed. To remove unreacted products, thecrystalline compound was dissolved in DMSO and precipitated withmethanol. The resulting crystalline precipitates were filtered bysuction, washed, and dried in an oven to provide 12.7 g of the lightfastcolorant of formula (10).

SYNTHESIS EXAMPLE 8

[0089] A lightfast colorant of formula (11) below was synthesized byreacting the benzophenone derivative obtained in Synthesis Example 2with the direct dye C.I. DIRECT BLACK 168.

[0090] A 250-mL round-bottomed flask equipped with a reflux condenserwas charged with 150 mL of an ethyl acetate solvent, 8.9 g of thebenzophenone derivative obtained in Synthesis Example 2, and 16.6 g ofC.I. DIRECT BLACK 168, and the reactants were dissolved in the solvent.

[0091] 10 mL of conc. sulfuric acid was slowly added together with oneor two boiling chips into the mixture and refluxed for 12 hours orlonger. The reaction product was washed with distilled water, and theorganic phase was collected. This organic phase was concentrated andrecrystallized to provide 17.3 g of the lightfast colorant of formula(11).

SYNTHESIS EXAMPLE 9

[0092] A lightfast colorant of formula (12) below was synthesized byreacting the benzophenone derivative obtained in Synthesis Example 2with an acid dye C.I. ACID BLACK 191.

[0093] 8.9 g of the benzophenone derivative obtained in SynthesisExample 2 was dissolved in 150 mL of DMSO in a 500-mL round-bottomedflask equipped with a reflux condenser. 3.0 g of SOCl₂ was added to themixture and reacted at room temperature for 1 hour or longer.

[0094] A solution of 19.3 g of C.I. ACID BLACK 191 in 200 mL of DMSO wasadded into the flask, together with one or two boiling chips and reactedat 80° C. for 8 hours or longer. The reaction product was cooled to roomtemperature, and excess methanol was added to precipitate a desiredcrystalline compound. The crystalline precipitates were filtered bysuction and washed. To remove unreacted products, the crystallinecompound was dissolved in DMSO and precipitated with methanol. Theresulting crystalline precipitates were filtered by suction, washed, anddried in an oven to provide 18.5 g of the lightfast colorant of formula(12).

SYNTHESIS EXAMPLE 10

[0095] A lightfast colorant of formula (13) below was synthesized byreacting the benzophenone derivative obtained in Synthesis Example 2with C.I. PIGMENT RED 177.

[0096] 8.9 g of the benzophenone derivative obtained in SynthesisExample 2 was dissolved in 150 mL of DMSO in a 500-mL round-bottomedflask equipped with a reflux condenser. 3.0 g of SOCl₂ was added to themixture and reacted at room temperature for 1 hour or longer. A solutionof 8.7 g of C.I. PIGMENT RED 177 in 200 mL of DMSO was added to theflask together with one or two boiling chips and reacted at 80° C. for 8hours or longer. The reaction product was cooled to room temperature,and excess methanol was added to precipitate a desired crystallinecompound. The crystalline precipitates were filtered by suction andwashed. To remove unreacted products, the crystalline compound wasdissolved in DMSO and precipitated with methanol. The resultingcrystalline precipitates were filtered by suction, washed, and dried inan oven to provide 13.3 g of the lightfast colorant of formula (13).

SYNTHESIS EXAMPLE 11

[0097] A lightfast colorant of formula (14) below was synthesized byreacting the benzophenone derivative obtained in Synthesis Example 3with a direct dye C.I. DIRECT BLACK 51.

[0098] 14.3 g of C.I. DIRECT BLACK 51 was dissolved in 150 mL of DMSO ina 500-mL round-bottomed flask equipped with a reflux condenser. 3.0 g ofSOCl₂ was added to the mixture and reacted at room temperature for 1hour or longer. A solution of 7.6 g of the benzophenone derivativeobtained in Synthesis Example 3 in 200 mL of DMSO was added into theflask together with one or two boiling chips and reacted at 80° C. for 8hours or longer. The reaction product was cooled to room temperature,and excess methanol was added to precipitate a desired crystallinecompound. The crystalline precipitates were filtered by suction andwashed. To remove unreacted products, the crystalline compound wasdissolved in DMSO and precipitated with methanol. The resultingcrystalline precipitates were filtered by suction, washed, and dried inan oven to provide 14.7 g of the lightfast colorant of formula (14).

SYNTHESIS EXAMPLE 12

[0099] A lightfast colorant of formula (15) below was synthesized byreacting the benzophenone derivative obtained in Synthesis Example 4with the direct dye C.I. DIRECT BLACK 51.

[0100] 14.3 g of C.I. DIRECT BLACK 51 was dissolved in 150 mL of DMSO ina 500-mL round-bottomed flask equipped with a reflux condenser. 3.0 g ofSOCl₂ was added to the mixture and reacted at room temperature for 1hour or longer. A solution of 7.9 g of the benzophenone derivativeobtained in Synthesis Example 4 in 200 mL of DMSO was added to the flasktogether with one or two boiling chips and reacted at 80° C. for 8 hoursor longer. The reaction product was cooled to room temperature, andexcess methanol was added to precipitate a desired crystalline compound.The crystalline precipitates were filtered by suction and washed. Toremove unreacted products, the crystalline compound was dissolved inDMSO and precipitated with methanol. The resulting crystallineprecipitates were filtered by suction, washed, and dried in an oven toprovide 15.7 g of the lightfast colorant of formula (15).

SYNTHESIS EXAMPLE 13

[0101] A lightfast colorant of formula (16) below was synthesized byreacting the benzophenone derivative obtained in Synthesis Example 4with C.I. PIGMENT RED 57.

[0102] 10.2 g of C.I. PIGMENT RED 57 was dissolved in 150 mL of DMSO ina 500-mL round-bottomed flask equipped with a reflux condenser. 3.0 g ofSOCl₂ was added to the mixture and reacted at room temperature for 1hour or longer. A solution of 7.9 g of the benzophenone derivativeobtained in Synthesis Example 4 in 200 mL of DMSO was added to the flasktogether with one or two boiling chips and reacted at 80° C. for 8 hoursor longer. The reaction product was cooled to room temperature, andexcess methanol was added to precipitate a desired crystalline compound.The crystalline precipitates were filtered by suction and washed. Toremove unreacted products, the crystalline compound was dissolved inDMSO and precipitated with methanol. The resulting crystallineprecipitates were filtered by suction, washed, and dried in an oven toprovide 11.5 g of the lightfast colorant of formula (16).

SYNTHESIS EXAMPLE 14

[0103] A lightfast colorant of formula (17) below was synthesized byreacting the benzophenone derivative obtained in Synthesis Example 5with C.I. PIGMENT RED 57.

[0104] 10.2 g of C.I. PIGMENT RED 57 was dissolved in 150 mL of DMSO ina 500-mL round-bottomed flask equipped with a reflux condenser. 3.0 g ofSOCl₂ was added to the mixture and reacted at room temperature for 1hour or longer. A solution of 7.5 g of the benzophenone derivativeobtained in Synthesis Example 5 in 200 mL of DMSO was added to the flasktogether with one or two boiling chips and reacted at 80° C. for 8 hoursor longer. The reaction product was cooled to room temperature, andexcess methanol was added to precipitate a desired crystalline compound.The crystalline precipitates were filtered by suction and washed. Toremove unreacted products, the crystalline compound was dissolved inDMSO and precipitated with methanol. The resulting crystallineprecipitates were filtered by suction, washed, and dried in an oven toprovide 12.5 g of the lightfast colorant of formula (17).

Example 1 Ink Composition

[0105] COMPONENT CONTENT C.I. DIRECT BLACK 168  3 g Lightfast Colorantof Synthesis Example 6  1 g Water 77 g Isopropyl alcohol  3 g Ethyleneglycol 10 g Glycerin  6 g

[0106] The above-listed components were mixed together and stirred forabout 30 minutes or longer to obtain a homogeneous composition. Thiscomposition was passed through a 0.45-μm filter to provide a lightfastink composition according to an embodiment of the present invention.

Example 2

[0107] A lightfast ink composition according to an embodiment of thepresent invention was prepared in the same manner as in Example 1,except that C.I. ACID YELLOW 23 instead of C.I. DIRECT BLACK 168 and thelightfast colorant obtained in Synthesis Example 7 instead of thelightfast colorant obtained in Synthesis Example 6 were used.

Example 3

[0108] A lightfast ink composition according to an embodiment of thepresent invention was prepared in the same manner as in Example 1,except that the lightfast colorant obtained in Synthesis Example 8instead of the lightfast colorant obtained in Synthesis Example 6 wasused.

Example 4

[0109] A lightfast ink composition according to an embodiment of thepresent invention was prepared in the same manner as in Example 1,except that C.I. ACID BLACK 191 instead of C.I. DIRECT BLACK 168 and thelightfast colorant obtained in Synthesis Example 9 instead of thelightfast colorant obtained in Synthesis Example 6 were used.

Example 5 Ink Composition

[0110] COMPONENT CONTENT C.I. PIGMENT RED 177  3 g Lightfast Colorant ofSynthesis Example 10  1 g Water 73 g Glycerin  4 g 1,5 pentanediol  8 g2-pyrrolidone  6 g TEGO DISPERSE 750 W  5 g

[0111] The above-listed components were mixed together and stirred forabout 30 minutes or longer to obtain a homogeneous composition. Thiscomposition was passed through a 0.8-μm filter to provide a lightfastink composition according to an embodiment of the present invention.

Example 6

[0112] A lightfast ink composition according to an embodiment of thepresent invention was prepared in the same manner as in Example 1,except that C.I. DIRECT BLACK 51 instead of C.I. DIRECT BLACK 168 andthe lightfast colorant obtained in Synthesis Example 11 instead of thelightfast colorant obtained in Synthesis Example 6 were used.

Example 7

[0113] A lightfast ink composition according to an embodiment of thepresent invention was prepared in the same manner as in Example 1,except that C.I. DIRECT BLACK 51 instead of C.I. DIRECT BLACK 168 andthe lightfast colorant obtained in Synthesis Example 12 instead of thelightfast colorant obtained in Synthesis Example 6 were used.

Example 8 Ink Composition

[0114] COMPONENT CONTENT C.I. PIGMENT RED 57 3 g Lightfast Colorant ofSynthesis Example 13  1 g Water 73 g Glycerin  4 g Diethylene glycol  8g 2-pyrrolidone  6 g TEGO DISPERSE 750 W  5 g

[0115] The above-listed components were mixed together and stirred forabout 30 minutes or longer to obtain a homogeneous composition. Thiscomposition was passed through a 0.8-μm filter to provide a lightfastink composition according to an embodiment of the present invention.

Example 9

[0116] A lightfast ink composition according to an embodiment of thepresent invention was prepared in the same manner as in Example 8,except that the lightfast colorant obtained in Synthesis Example 14instead of the lightfast colorant obtained in Synthesis Example 13 wasused.

Example 10

[0117] A lightfast ink composition according to an embodiment of thepresent invention was prepared in the same manner as in Example 1,except that 4 g of the lightfast colorant obtained in Synthesis Example6 was used alone as the colorant component, without using C.I. DIRECTBLACK 168.

Comparative Example 1

[0118] An ink composition was prepared in the same manner as in Example1, except that 4 g of C.I. DIRECT BLACK 168 was used alone as thecolorant component, without using the lightfast colorant of SynthesisExample 6.

Comparative Example 2

[0119] An ink composition was prepared in the same manner as in Example2, except that 4 g of C.I. ACID YELLOW 23 was used alone as the colorantcomponent, without using the lightfast colorant of Synthesis Example 7.

Comparative Example 3

[0120] An ink composition was prepared in the same manner as in Example4, except that 4 g of C.I. ACID BLACK 191 was used alone as the colorantcomponent, without using the lightfast colorant of Synthesis Example 9.

Comparative Example 4

[0121] An ink composition was prepared in the same manner as in Example6, except that 4 g of C.I. DIRECT BLACK 51 was used alone as thecolorant component, without using the lightfast colorant of SynthesisExample 11.

Comparative Example 5

[0122] An ink composition was prepared in the same manner as in Example5, except that 4 g of C.I. PIGMENT RED 177 was used alone as thecolorant component, without using the lightfast colorant of SynthesisExample 10.

Comparative Example 6

[0123] An ink composition was prepared in the same manner as in Example8, except that 4 g of C.I. PIGMENT RED 57 was used alone as the colorantcomponent, without using the lightfast colorant of Synthesis Example 13.

Comparative Example 7

[0124] An ink composition was prepared in the same manner as inComparative Example 1, except that 0.2 g of octylmethoxybenzophenone wasfurther added as a lightfastness enhancer.

Comparative Example 8

[0125] An ink composition was prepared in the same manner as inComparative Example 2, except that 0.2 g of octylmethoxybenzophenone wasfurther added as a lightfastness enhancer.

Comparative Example 9

[0126] An ink composition was prepared in the same manner as inComparative Example 3, except that 0.2 g of octylmethoxybenzophenone wasfurther added as a lightfastness enhancer.

Comparative Example 10

[0127] An ink composition was prepared in the same manner as inComparative Example 4, except that 0.2 g of octylmethoxybenzophenone wasfurther added as a lightfastness enhancer.

[0128] The lightfastness and the anti-clogging property of the inkcompositions prepared in the above examples and comparative exampleswere evaluated as follows.

[0129] Storage Stability (Anti-Clogging Property) Test

[0130] 100 mL of samples of the ink compositions prepared in Examples 1through 10 and Comparative Examples 1 through 10 were portioned intorespective heat-resistant glass bottles. The glass bottles were sealedand stored in a 60° C.-water bath for 2 months. It was observed whetherprecipitates appeared in the bottles. The results are shown in Table 1.In Table 1, 0 indicates that no precipitate appeared, and X indicatesthat precipitates appeared. TABLE 1 Example Comparative Example No. 1 23 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10 Result 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 X X X X

[0131] As shown in Table 1, for the ink compositions prepared inExamples 1 through 10, which contain the lightfast colorants accordingto embodiments of the present invention, no precipitates appear,indicating that the ink compositions according to embodiments of thepresent invention have better long-term storage stability than the inkcompositions of Comparative Examples 7 through 10, that contain theconventional colorants and the lightfastness enhancer and precipitate.

[0132] Lightfastness Test

[0133] 2×2 cm solid patterns were printed using the ink compositions ofExamples 1 through 10 and Comparative Examples 1 through 10 and an inkjet printer (MJC 1130i, available from SAMSUNG ELECTRONICS CO.). Theprinted results were exposed to light for 100 hours in a Q-SUN XENONTEST CHAMBER. Optical density (OD) was measured before and after lightexposure, and A values (lightfastness values) were calculated using thefollowing equation. Lightfastness was evaluated as good (G) for A≧90,moderate (M) for 75≦A<90, and poor (X) for A<75. The results are shownin Table 2.

A=OD after exposure/OD before exposure×100(%)

[0134] TABLE 2 Example Comparative Example No. 1 2 3 4 5 6 7 8 9 10 1 23 4 5 6 7 8 9 10 Result G G G G G G G G G G X X X X M M G G G G

[0135] As shown in Table 2, the ink compositions prepared in Examples 1through 10, which contain the lightfast colorants according toembodiments of the present invention, have improved lightfastness at Avalues of 90% or more. However, the ink compositions prepared inComparative Examples 1 through 6, which contain the conventionalcolorants, have lightfastness values of less than 90%. Evidently, theink compositions according to embodiments of the present invention haveimproved lightfastness compared to the conventional ink compositions.

[0136] As described above, lightfast colorants according to embodimentsof the present invention, which are derived by covalently binding alightfast benzophenone derivative and a conventional colorant, haveimproved lightfastness. When such a lightfast colorant according to anembodiment of the present invention is added to an ink composition, thestorage stability as well as the lightfastness of the ink compositionare improved.

[0137] Although a few embodiments of the present invention have beenshown and described, it would be appreciated by those skilled in the artthat changes may be made in these embodiments without departing from theprinciples and spirit of the invention, the scope of which is defined inthe claims and their equivalents.

What is claimed is:
 1. A lightfast colorant that is a benzophenonederivative of formula (1) below:

wherein Y₁ is one selected from the group consisting of —H, —OH, —NH₂,—NHR₁, —N(R₁)₂, —SH, and a C₁-C₃₀ heteroalkyl group, where R₁ is a C₁-C₆alkyl group; each of Y₂ and Y₃ is independently selected from the groupconsisting of —H, —OH, —NH₂, —NHR₁, —N(R₁)₂, where R₁ is a C₁-C₆ alkylgroup, —SH, a substituted or unsubstituted C₁-C₃₀ alkyl group, asubstituted or unsubstituted C₁-C₃₀ alkenyl group, a substituted orunsubstituted C₁-C₃₀ alkynyl group, a substituted or unsubstitutedC₁-C₃₀ heteroalkyl group, a substituted or unsubstituted C₆-C₃₀ arylgroup, a substituted or unsubstituted C₇-C₃₀ arylalkyl group, asubstituted or unsubstituted C₃-C₃₀ heteroaryl group, and a substitutedor unsubstituted C₄-C₃₀ heteroarylalkyl group; n is an integer from 0 to6; R is selected from the group consisting of a substituted orunsubstituted C₁-C₃₀ alkylene group, a substituted or unsubstitutedC₁-C₃₀ alkenylene group, a substituted or unsubstituted C₁-C₃₀alkynylene group, a substituted or unsubstituted C₁-C₃₀ heteroalkylenegroup, a substituted or unsubstituted C₆-C₃₀ arylene group, asubstituted or unsubstituted C₇-C₃₀ arylenealkylene group, a substitutedor unsubstituted C₃-C₃₀ heteroarylene group, and a substituted orunsubstituted C₄-C₃₀ heteroarylenealkylene group; X is a linker selectedfrom the group consisting of —CONH—, —NHCO—, —COO—, —OCO—, —CO—, —O—,—S—, —SO₂—, —SO₃—, —O—P(═O)(OH)—O—, and —O—P(OH)—O—; and Y is a colorantresidue.
 2. The lightfast colorant of claim 1, wherein said colorantresidue Y is a moiety of one of a dye and a pigment used as a colorant,the moiety excludes said linker X, and said linker X binds the colorantand the benzophenone derivative.
 3. A lightfast ink compositioncomprising: at least one lightfast colorant that is a benzophenonederivative of formula (1) below:

wherein Y₁ is one selected from the group consisting of —H, —OH, —NH₂,—NHR₁, —N(R₁)₂, —SH, and a C₁-C₃₀ heteroalkyl group, where R₁ is a C₁-C₆alkyl group; each of Y₂ and Y₃ is independently selected from the groupconsisting of —H, —OH, —NH₂, —NHR₁, —N(R₁)₂, where R₁ is a C₁-C₆ alkylgroup, —SH, a substituted or unsubstituted C₁-C₃₀ alkyl group, asubstituted or unsubstituted C₁-C₃₀ alkenyl group, a substituted orunsubstituted C₁-C₃₀ alkynyl group, a substituted or unsubstitutedC₁-C₃₀ heteroalkyl group, a substituted or unsubstituted C₆-C₃₀ arylgroup, a substituted or unsubstituted C₇-C₃₀ arylalkyl group, asubstituted or unsubstituted C₃-C₃₀ heteroaryl group, and a substitutedor unsubstituted C₄-C₃₀ heteroarylalkyl group; n is an integer from 0 to6; R is selected from the group consisting of a substituted orunsubstituted C₁-C₃₀ alkylene group, a substituted or unsubstitutedC₁-C₃₀ alkenylene group, a substituted or unsubstituted C₄-C₃₀alkynylene group, a substituted or unsubstituted C₁-C₃₀ heteroalkylenegroup, a substituted or unsubstituted C₆-C₃₀ arylene group, asubstituted or unsubstituted C₇-C₃₀ arylenealkylene group, a substitutedor unsubstituted C₃-C₃₀ heteroarylene group, and a substituted orunsubstituted C₄-C₃₀ heteroarylenealkylene group; X is a linker selectedfrom the group consisting of —CONH—, —NHCO—, —COO—, —OCO—, —CO—, —O—,—S—, —SO₂—, —SO₃—, —O—P(═O)(OH)—O—, and —O—P(OH)—O—; and Y is a colorantresidue; and an aqueous medium.
 4. The lightfast ink composition ofclaim 3, wherein the amount of the lightfast colorant is in the range of0.1-20 parts by weight with respect to 100 parts by weight of the inkcomposition.
 5. A lightfast ink composition comprising: a colorant; atleast one lightfast colorant that is a benzophenone derivative offormula (1) below:

wherein Y₁ is one selected from the group consisting of —H, —OH, —NH₂,—NHR₁, —N(R₁)₂, —SH, and a C₁-C₃₀ heteroalkyl group, where R₁ is a C₁-C₆alkyl group; each of Y₂ and Y₃ is independently selected from the groupconsisting of —H, —OH, —NH₂, —NHR₁, —N(R₁)₂, where R₁ is a C₁-C₆ alkylgroup, —SH, a substituted or unsubstituted C₁-C₃₀ alkyl group, asubstituted or unsubstituted C₁-C₃₀ alkenyl group, a substituted orunsubstituted C₁-C₃₀ alkynyl group, a substituted or unsubstitutedC₁-C₃₀ heteroalkyl group, a substituted or unsubstituted C₆-C₃₀ arylgroup, a substituted or unsubstituted C₇-C₃₀ arylalkyl group, asubstituted or unsubstituted C₃-C₃₀ heteroaryl group, and a substitutedor unsubstituted C₄-C₃₀ heteroarylalkyl group; n is an integer from 0 to6; R is selected from the group consisting of a substituted orunsubstituted C₁-C₃₀ alkylene group, a substituted or unsubstitutedC₁-C₃₀ alkenylene group, a substituted or unsubstituted C₁-C₃₀alkynylene group, a substituted or unsubstituted C₁-C₃₀ heteroalkylenegroup, a substituted or unsubstituted C₆-C₃₀ arylene group, asubstituted or unsubstituted C₇-C₃₀ arylenealkylene group, a substitutedor unsubstituted C₃-C₃₀ heteroarylene group, and a substituted orunsubstituted C₄-C₃₀ heteroarylenealkylene group; X is a linker selectedfrom the group consisting of —CONH—, —NHCO—, —COO—, —OCO—, —CO—, —O—,—S—, —SO₂—, —SO₃—, —O—P(═O)(OH)—O—, and —O—P(OH)—O—; and Y is a colorantresidue; and an aqueous medium.
 6. The lightfast ink composition ofclaim 5, wherein the amount of the colorant is in the range of 1-25parts by weight, the amount of the lightfast colorant is in the range of0.1-20 parts by weight, and the total amount of the colorant and thelightfast colorant is in the range of 1.1-45 parts by weight, withrespect to 100 parts by weight of the lightfast ink composition.
 7. Thelightfast ink composition of claim 3, wherein the aqueous medium is oneof water and a mixture of 5-10% by weight of an organic solvent and50-95% by weight of water.
 8. The lightfast ink composition of claim 7,wherein the organic solvent is selected from the group consisting ofmethyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol,n-butyl alcohol, sec-butyl alcohol, t-butyl alcohol, isobutyl alcohol,acetone, methylethyl ketone, diacetone alcohol, methyl acetate, ethylacetate, ethyl lactate, ethylene glycol, diethylene glycol, triethyleneglycol, propylene glycol, butylene glycol, 1,4-butane diol, 1,2,4-butanetriol, 1,5-pentanediol, 1,2,6-hexane triol, hexylene glycol, glycerol,glycerol ethoxylate, trimethylolpropane ethoxylate, ethylene glycolmonomethyl ether, ethylene glycol monoethyl ether, diethylene glycolmethyl ether, diethylene glycol ethyl ether, triethylene glycolmonomethyl ether, triethylene glycol monoethyl ether, 2-pyrrolidone,N-methyl-2-pyrrolidone, dimethyl sulfoxide, tetramethylene sulfone, andthioglycol.
 9. The lightfast ink composition of claim 3, furthercomprising at least one additive selected from the group consisting of adispersant, a viscosity adjuster, a surfactant, a storage stabilizer,and a wetting agent, wherein the amount of the at least one additive isin a range of 0.5-40 parts by weight with respect to 100 parts by weightof the lightfast ink composition.
 10. The lightfast ink composition ofclaim 5, wherein the aqueous medium is one of water and a mixture of5-10% by weight of an organic solvent and 50-95% by weight of water. 11.The lightfast ink composition of claim 5, further comprising at leastone additive selected from the group consisting of a dispersant, aviscosity adjuster, a surfactant, a storage stabilizer, and a wettingagent, wherein the amount of the at least one additive is in a range of0.5-40 parts by weight with respect to 100 parts by weight of thelightfast ink composition.
 12. The lightfast ink composition of claim 3,comprising: at least one lightfast colorant of formula (3) below:

wherein Y₁ is one selected from the group consisting of —H, —OH, —NH₂,—NHR₁, —N(R₁)₂, —SH, and a C₁-C₃₀ heteroalkyl group, where R₁ is a C₁-C₆alkyl group; each of Y₂ and Y₃ is independently selected from the groupconsisting of —H, —OH, —NH₂, —NHR₁, —N(R₁)₂, where R₁ is a C₁-C₆ alkylgroup, —SH, a substituted or unsubstituted C₁-C₃₀ alkyl group, asubstituted or unsubstituted C₁-C₃₀ alkenyl group, a substituted orunsubstituted C₁-C₃₀ alkynyl group, a substituted or unsubstitutedC₁-C₃₀ heteroalkyl group, a substituted or unsubstituted C₆-C₃₀ arylgroup, a substituted or unsubstituted C₇-C₃₀ arylalkyl group, asubstituted or unsubstituted C₃-C₃₀ heteroaryl group, and a substitutedor unsubstituted C₄-C₃₀ heteroarylalkyl group; n is an integer from 0 to6; R is selected from the group consisting of a substituted orunsubstituted C₁-C₃₀ alkylene group, a substituted or unsubstitutedC₁-C₃₀ alkenylene group, a substituted or unsubstituted C₁-C₃₀alkynylene group, a substituted or unsubstituted C₁-C₃₀ heteroalkylenegroup, a substituted or unsubstituted C₆-C₃₀ arylene group, asubstituted or unsubstituted C₇-C₃₀ arylenealkylene group, a substitutedor unsubstituted C₃-C₃₀ heteroarylene group, and a substituted orunsubstituted C₄-C₃₀ heteroarylenealkylene group; X is a linker selectedfrom the group consisting of —CONH—, —NHCO—, —COO—, —OCO—, —CO—, —O—,—S—, —SO₂—, —SO₃—, —O—P(═O)(OH)—O—, and —O—P(OH)—O—; and Y is a colorantresidue; and an aqueous medium.
 13. The lightfast ink composition ofclaim 3, comprising: at least one lightfast colorant of formula (4)below:

wherein Y₁ is one selected from the group consisting of —H, —OH, —NH₂,—NHR₁, —N(R₁)₂, —SH, and a C₁-C₃₀ heteroalkyl group, where R₁ is a C₁-C₆alkyl group; each of Y₂ and Y₃ is independently selected from the groupconsisting of —H, —OH, —NH₂, —NHR₁, —N(R₁)₂, where R₁ is a C₁-C₆ alkylgroup, —SH, a substituted or unsubstituted C₁-C₃₀ alkyl group, asubstituted or unsubstituted C₁-C₃₀ alkenyl group, a substituted orunsubstituted C₁-C₃₀ alkynyl group, a substituted or unsubstitutedC₁-C₃₀ heteroalkyl group, a substituted or unsubstituted C₆-C₃₀ arylgroup, a substituted or unsubstituted C₇-C₃₀ arylalkyl group, asubstituted or unsubstituted C₃-C₃₀ heteroaryl group, and a substitutedor unsubstituted C₄-C₃₀ heteroarylalkyl group; n is an integer from 0 to6; R is selected from the group consisting of a substituted orunsubstituted C₁-C₃₀ alkylene group, a substituted or unsubstitutedC₁-C₃₀ alkenylene group, a substituted or unsubstituted C₁-C₃₀alkynylene group, a substituted or unsubstituted C₁-C₃₀ heteroalkylenegroup, a substituted or unsubstituted C₆-C₃₀ arylene group, asubstituted or unsubstituted C₇-C₃₀ arylenealkylene group, a substitutedor unsubstituted C₃-C₃₀ heteroarylene group, and a substituted orunsubstituted C₄-C₃₀ heteroarylenealkylene group; X is a linker selectedfrom the group consisting of —CONH—, —NHCO—, —COO—, —OCO—, —CO—, —O—,—S—, —SO₂—, —SO₃—, —O—P(═O)(OH)—O—, and —O—P(OH)—O—; and Y is a colorantresidue; and an aqueous medium.
 14. The lightfast ink composition ofclaim 3, comprising: at least one lightfast colorant of formula (5)below:

wherein Y₁ is one selected from the group consisting of —H, —OH, —NH₂,—NHR₁, —N(R₁)₂, —SH, and a C₁-C₃₀ heteroalkyl group, where R₁ is a C₁-C₆alkyl group; each of Y₂ and Y₃ is independently selected from the groupconsisting of —H, —OH, —NH₂, —NHR₁, —N(R₁)₂, where R₁ is a C₁-C₆ alkylgroup, —SH, a substituted or unsubstituted C₁-C₃₀ alkyl group, asubstituted or unsubstituted C₁-C₃₀ alkenyl group, a substituted orunsubstituted C₁-C₃₀ alkynyl group, a substituted or unsubstitutedC₁-C₃₀ heteroalkyl group, a substituted or unsubstituted C₆-C₃₀ arylgroup, a substituted or unsubstituted C₇-C₃₀ arylalkyl group, asubstituted or unsubstituted C₃-C₃₀ heteroaryl group, and a substitutedor unsubstituted C₄-C₃₀ heteroarylalkyl group; n is an integer from 0 to6; R is selected from the group consisting of a substituted orunsubstituted C₁-C₃₀ alkylene group, a substituted or unsubstitutedC₁-C₃₀ alkenylene group, a substituted or unsubstituted C₁-C₃₀alkynylene group, a substituted or unsubstituted C₁-C₃₀ heteroalkylenegroup, a substituted or unsubstituted C₆-C₃₀ arylene group, asubstituted or unsubstituted C₇-C₃₀ arylenealkylene group, a substitutedor unsubstituted C₃-C₃₀ heteroarylene group, and a substituted orunsubstituted C₄-C₃₀ heteroarylenealkylene group; X is a linker selectedfrom the group consisting of —CONH—, —NHCO—, —COO—, —OCO—, —CO—, —O—,—S—, —SO₂—, —SO₃—, —O—P(═O)(OH)—O—, and —O—P(OH)—O—; and Y is a colorantresidue; and an aqueous medium.
 15. The lightfast ink composition ofclaim 3, comprising: at least one lightfast colorant of formula (6)below:

wherein Y₁ is one selected from the group consisting of —H, —OH, —NH₂,—NHR₁, —N(R₁)₂, —SH, and a C₁-C₃₀ heteroalkyl group, where R₁ is a C₁-C₆alkyl group; each of Y₂ and Y₃ is independently selected from the groupconsisting of —H, —OH, —NH₂, —NHR₁, —N(R₁)₂, where R₁ is a C₁-C₆ alkylgroup, —SH, a substituted or unsubstituted C₁-C₃₀ alkyl group, asubstituted or unsubstituted C₁-C₃₀ alkenyl group, a substituted orunsubstituted C₁-C₃₀ alkynyl group, a substituted or unsubstitutedC₁-C₃₀ heteroalkyl group, a substituted or unsubstituted C₆-C₃₀ arylgroup, a substituted or unsubstituted C₇-C₃₀ arylalkyl group, asubstituted or unsubstituted C₃-C₃₀ heteroaryl group, and a substitutedor unsubstituted C₄-C₃₀ heteroarylalkyl group; n is an integer from 0 to6; R is selected from the group consisting of a substituted orunsubstituted C₁-C₃₀ alkylene group, a substituted or unsubstitutedC₁-C₃₀ alkenylene group, a substituted or unsubstituted C₁-C₃₀alkynylene group, a substituted or unsubstituted C₁-C₃₀ heteroalkylenegroup, a substituted or unsubstituted C₆-C₃₀ arylene group, asubstituted or unsubstituted C₇-C₃₀ arylenealkylene group, a substitutedor unsubstituted C₃-C₃₀ heteroarylene group, and a substituted orunsubstituted C₄-C₃₀ heteroarylenealkylene group; X is a linker selectedfrom the group consisting of —CONH—, —NHCO—, —COO—, —OCO—, —CO—, —O—,—S—, —SO₂—, —SO₃—, —O—P(═O)(OH)—O—, and —O—P(OH)—O—; and Y is a colorantresidue; and an aqueous medium.
 16. The lightfast ink composition ofclaim 3, comprising: at least one lightfast colorant of formula (7)below:

wherein Y₁ is one selected from the group consisting of —H, —OH, —NH₂,—NHR₁, —N(R₁)₂, —SH, and a C₁-C₃₀ heteroalkyl group, where R₁ is a C₁-C₆alkyl group; each of Y₂ and Y₃ is independently selected from the groupconsisting of —H, —OH, —NH₂, —NHR₁, —N(R₁)₂, where R₁ is a C₁-C₆ alkylgroup, —SH, a substituted or unsubstituted C₁-C₃₀ alkyl group, asubstituted or unsubstituted C₁-C₃₀ alkenyl group, a substituted orunsubstituted C₁-C₃₀ alkynyl group, a substituted or unsubstitutedC₁-C₃₀ heteroalkyl group, a substituted or unsubstituted C₆-C₃₀ arylgroup, a substituted or unsubstituted C₇-C₃₀ arylalkyl group, asubstituted or unsubstituted C₃-C₃₀ heteroaryl group, and a substitutedor unsubstituted C₄-C₃₀ heteroarylalkyl group; n is an integer from 0 to6; R is selected from the group consisting of a substituted orunsubstituted C₁-C₃₀ alkylene group, a substituted or unsubstitutedC₁-C₃₀ alkenylene group, a substituted or unsubstituted C₁-C₃₀alkynylene group, a substituted or unsubstituted C₁-C₃₀ heteroalkylenegroup, a substituted or unsubstituted C₆-C₃₀ arylene group, asubstituted or unsubstituted C₇-C₃₀ arylenealkylene group, a substitutedor unsubstituted C₃-C₃₀ heteroarylene group, and a substituted orunsubstituted C₄-C₃₀ heteroarylenealkylene group; X is a linker selectedfrom the group consisting of —CONH—, —NHCO—, —COO—, —OCO—, —CO—, —O—,—S—, —SO₂—, —SO₃—, —O—P(═O)(OH)—O—, and —O—P(OH)—O—; and Y is a colorantresidue; and an aqueous medium.
 17. The lightfast ink composition ofclaim 3, comprising: at least one lightfast colorant of formula (8)below:

wherein Y₁ is one selected from the group consisting of —H, —OH, —NH₂,—NHR₁, —N(R₁)₂, —SH, and a C₁-C₃₀ heteroalkyl group, where R₁ is a C₁-C₆alkyl group; each of Y₂ and Y₃ is independently selected from the groupconsisting of —H, —OH, —NH₂, —NHR₁, —N(R₁)₂, where R₁ is a C₁-C₆ alkylgroup, —SH, a substituted or unsubstituted C₁-C₃₀ alkyl group, asubstituted or unsubstituted C₁-C₃₀ alkenyl group, a substituted orunsubstituted C₁-C₃₀ alkynyl group, a substituted or unsubstitutedC₁-C₃₀ heteroalkyl group, a substituted or unsubstituted C₆-C₃₀ arylgroup, a substituted or unsubstituted C₇-C₃₀ arylalkyl group, asubstituted or unsubstituted C₃-C₃₀ heteroaryl group, and a substitutedor unsubstituted C₄-C₃₀ heteroarylalkyl group; n is an integer from 0 to6; R is selected from the group consisting of a substituted orunsubstituted C₁-C₃₀ alkylene group, a substituted or unsubstitutedC₁-C₃₀ alkenylene group, a substituted or unsubstituted C₁-C₃₀alkynylene group, a substituted or unsubstituted C₁-C₃₀ heteroalkylenegroup, a substituted or unsubstituted C₆-C₃₀ arylene group, asubstituted or unsubstituted C₇-C₃₀ arylenealkylene group, a substitutedor unsubstituted C₃-C₃₀ heteroarylene group, and a substituted orunsubstituted C₄-C₃₀ heteroarylenealkylene group; X is a linker selectedfrom the group consisting of —CONH—, —NHCO—, —COO—, —OCO—, —CO—, —O—,—S—, —SO₂—, —SO₃—, —O—P(═O)(OH)—O—, and —O—P(OH)—O—; and Y is a colorantresidue; and an aqueous medium.